


Fired Up

by b0o



Category: Undertale (Video Game)
Genre: Established Relationship, M/M, Mpreg, Undertale Genocide Route, grillby is pissed, skelepreg
Language: English
Status: Completed
Published: 2016-06-03
Updated: 2016-06-03
Packaged: 2018-07-11 23:04:30
Rating: Not Rated
Warnings: Creator Chose Not To Use Archive Warnings
Chapters: 1
Words: 1,891
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/7074244
Author URL: https://archiveofourown.org/users/b0o/pseuds/b0o
Summary: <blockquote class="userstuff">
              <p>I’ve seen some stuff were Sans was pregnant when fighting the human, and my recent love of Sansby inspired me to give it a try.</p>
            </blockquote>





	Fired Up

**Author's Note:**

> Sadness is fun.

Sans watched as Grillby went around the bar, he had barricaded the doors and windows first and now was just placing random objects next to the chairs and tables that acted as a blockade. It didn’t really matter because Snowdin was completely empty, the other residents had been quick to evacuate, and the human wasn’t likely to return. 

Sans had tried to convince his flamed lover to go with the others but gave up when Grillby made it apparent that where Sans went he would follow. In past resets he had gone along and evacuated, but when the time came for Sans to lay judgment it was almost impossible to distract his boyfriend long enough to teleport away. 

After he had to turn the others soul blue and push him back in one timeline, he decided it was easier to just keep him busy in the bar.

Stroking his large stomach he felt the soul within it move rapidly and a small pain that he knew would only grow worse. “hey hot stuff, i think you can take a moment to cool down a little.” 

Though he had done this before it didn’t keep the guilt from settling in his soul when Grillby stilled, unsure what to do until Sans let out a shaky breath after another pull.

He immediately got down to the skeletons height and put a hand on his shoulder. “…Are you alright?” His gaze went to Sans’s hand over his stomach, “…the child.” It wasn’t a question, and Grillby hesitantly reached to pull the hem of the shirt up. 

Sans didn’t say anything until his shirt was pulled up completely and the light blue glow of his stomach made him look down. Inside the protective membrane the dark blue oval that housed the tiny soul inside had become opaque and had moved to where the most magic was being supplied. 

“it’s still pretty early in the process, we got some time before the kid makes like a tree and splits.” As if knowing their parents were talking about them the tiny soul moved and glowed brightly, prompting a wince from Sans that did not go unnoticed by the other monster.

“Are you all right? I know that discomfort and slight pain are normal at this stage but it shouldn’t be strong yet.” The flames that made up his body grow hotter and brighter, he knew that if something were to go wrong that there would be little he could do. 

Already this was risky enough with just him to assist the soul split when the soul was still this young, Papyrus had been eager to donate his magic to Sans and the plan was that if Grillby wasn’t enough that he would help out.

Though he had no way of knowing that things would turn out like this he still cursed himself for not being more careful with using his magic and trying to save it for this. The thought of Papyrus sent knife through his heart and he could only begin to imagine what this was like for Sans. 

He knew the smaller skeleton needed to talk about it, and he knew it was bad to just let it go but was worried that if Sans had a full breakdown that he or the child might not survive it. “doesn’t really hurt, kid’s just drainen my magic too fast for me to keep up.”

It took a lot willpower for Grillby not to scold his lover for not immediately telling him, for not remembering that he only had 1 Hp and his magic was the only keeping the small soul from taking too much from him. Instead he scooped him into his arms and concentrated his magic to the other, Sans practically melted into him.

“alright, think that's enough for now.” Grillby was reluctant to stop but swore silently he would make sure Sans didn’t dip to low, it took longer for either of them to let go of each other and when they did Grillby felt satisfied that Sans looked a little better than before. 

“Please tell me if you start to feel tired or ill in any way.” Sans gave him a small kiss on the cheek, “will do boss.” He rested a hand on his stomach, “so do you have any idea what we’ll need later, like towels or hot water.”

Grillby stood up and thought for a moment before nodding, “Yes I know I have towels and perhaps a sheet to cover them with after their born.” He looked at the back where he had his inventory warily, “go ahead and grab it now, you have some time before the real action starts.” 

Sans knew Grillby wasn’t comfortable leaving his side right now, but he also knew that Grillby always liked for things to be in order. Especially when he was stressed or needed to do something.

Almost nodding to himself Grillby cast one final look at his boyfriend before quickly going to retrieve what was needed. When he was halfway across the bar Sans teleported to his destination.

He heard the soft pitter patter of small feet and was soon greeted with the sight of the dust covered human.  
\------------------------------------------------------------------------------------------------------------------------------------------  
Sans tried to believe it was a good sign that the human was obviously growing angrier with each attack and were letting out grunts of frustration along pain each time they were hit. “just give it up kid.”

He knew they heard him but refused to so much as look at him before narrowly dodging a Gaster Blaster barrage. They swung wildly at him and he dodged easily, masking his increasing pain.

The tiny soul he carried didn’t know how to react to all the magic and stress and was beginning to try hard to gather enough magic to separate. Magic that Sans desperately needed right now, he was at the end of his rope though and if his special attack didn’t work then he would have just enough energy to teleport to Grillby’s and use any remaining magic on the soul before his wound dusted him.

Finally it came time to use his special attack and though he tried hard to fight off the weariness, he still fell asleep. When the knife came down he barely moved enough from getting hit and was surprised when the human pivoted and brought it down again.

Then the human was burning and Sans stared stupidly at the knife when it fell to the floor. “Sans!” Grillby raced forward and lifted him up and crushed him to his torso, even with the familiar heat warming his bones Sans couldn’t believe this was happening.

One moment the human was about to dust him the next moment they were dust themselves, in all the timelines Sans recalled this had never even remotely happened. His mind began making different speculations onto what was different when a strong pain had him trying to curl around his middle. 

Moving quickly Grillby set him against a pillar and lifted up his shirt, the soul gave a lurch and trembled slightly. 

Wordlessly Grilby placed one hand on the stomach and another over Sans’s chest and poured out his magic. Sans hissed a little at the sudden influx but felt less on the brink of dust with each passing second. 

Finally Grillby pulled away, he wanted so badly to give more but knew if he did then he was at risk of blacking out or Sans having an magic overload. 

The soul stopped quivering and Sans let out a sigh of relief that it stabilized, they would soon try to split again and was taking a moment to absorb more magic before that. 

Sans allowed himself a moment before gathering up his magic and slowly pouring it into the soul, who reacted by shaking and growing slightly but soon stopped. Already Sans felt exhausted but was determined to live long enough help his child even partially form. 

Grillby had been watching in confusion but realized what he was doing, “Sans stop! If you try to make the child split before their ready it’ll only hurt you.” His voice shook with emotion and Sans immediately recognized one as being anger. 

“woops, sorry.” Sans scratched the side of his skull and looked at Grillby who appeared to be a few seconds from screaming. “so, uh, thanks for earlier. things were getting a bit dicey there for a second.” 

That seemed to be the last straw for Grillby because he snapped his head up to glare at him, his flames growing larger and hotter. “Why?” His voice shook and Sans found himself unable to look at him, “i needed to be the one to fight the human, to try and stop them before they went to far. i know it doesn’t make sense to you and it doesn’t matter how many times i explain it but trust me-” 

A sharp pain cut him off as the soul decided to try once more to split and he weakly offered his magic, Grillby sat behind him and pulled him onto his lap providing his own magic. When the soul stopped they did as well, Sans was shaking and let himself lean back into the other. 

“After our child is born and you recover, you will tell me everything and leave nothing out.” The skeleton nodded weakly, he had come clean to almost everyone in a few timelines but when it didn’t work he decided it wasn’t worth it.

At another pull from the soul he felt Grillby’s magic try to compensate for his own and almost laughed because the flame monster was really the one that needed help right now. 

He couldn’t remember how many times he had dusted in his arms and remembered when he made the mistake to look at his face and saw pure anguish. Dimly he knew that Grillby was speaking to him currently what he assumed were words of encouragement but he couldn’t understand any of the sounds he was emitting, the only thing he was really aware of was the warmth that surrounded him.

He was tired but when the pain came he obediently gave the soul any magic he had, it was gaining more form and Sans knew that the final split would happen soon. “love you” whether Grillby heard him and didn’t respond , or if he just didn’t say it Sans didn’t know and didn’t have the energy or time to repeat it before a new pain struck him harder than the others.

In a small part in the back of his mind he found it surprising that he still had enough energy to scream as a piece of his soul literally broke off and the last of his magic ebbed away.

Sans no longer felt the familiar warmth around him though he knew Grillby was still there, darkness was beginning to enter his vision and he couldn’t see out of his right eye anymore. 

None of that mattered though, the only thing that mattered was the small skeleton with wispy flames for hair. Cracks covered the child and they were oddly quite, but Sans was just happy they hadn’t turned to dust and were in one piece. 

The last thing he saw before his vision grew completely black was his child opening their eyes to blink curiously at him.


End file.
